pre-order traversal, with recursion: 35 28 20 25 23 26 30 60 70 65 64 68 pre-order traversal, without recursion: 35 60 70 in-order traversal, with recursion: 20 23 25 26 28 30 35 60 64 65 68 70 in-order traversal, without recursion: 20 23 25 26 28 30 35 60 64 65 68 70